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We aim to investigate the effects of humic acid (HA) and citric acid (CA) on the toxicity and subcellular distribution of Cd in wheat. Results show that the toxicity and uptake of Cd decreased with increasing HA. The EC50 values of Cd increased from 3.36 μmol/L to 4.96 and 7.33 μmol/L at 50 and 250 mg/L HA, respectively, but decreased to 1.39 μmol/L in the presence of CA based on free ion activity model (FIAM). HA decreased the relative subcellular distribution of Cd in the heat-denatured proteins (decreased from 54% to 33%) but increased Cd in the heat-stable proteins in root (from 25% to 50%) at 7.61 μmol/L {Cd2+} (free Cd activity), which resulted in decreasing Cd toxicity. However, CA increased Cd toxicity due to the increased internalization of Cd although the relative subcellular distributions of Cd exhibited a decrease in the heat-denatured proteins and increase in the granule fraction compared to the control at high-level Cd. The FIAM could not predict the toxicity of Cd in the presence of organic acids. Alternatively, the internal Cd accumulation and subcellular Cd concentration were better to describe the toxicity of Cd to wheat. 相似文献
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Nitrobenzene is an important raw material and product,which presents a heavy threat to the ecosystem.The potential impacts of nitrobenzene on sediment oxygen demand (SOD) were studied in lake sediment ... 相似文献
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基于唐南渗析原理,采用阳离子交换膜去除原水中Cu2+、Mn2+、Zn2+等重金属离子,研究影响阳离子交换膜去除各重金属离子能力大小的机制以及2种重金属离子共存时互相干扰的机制.结果表明,阳离子交换膜可有效去除原水中Cu2+、Mn2+、Zn2+等重金属离子,去除率为75%~85%;在浓度相同下且重金属离子带相同电荷数时,其水化离子半径越小,离子扩散速度就越快,阳离子交换膜对其去除能力就越强;当重金属水化离子半径基本相同时,膜对原子序数小的重金属离子的去除能力更强;相同浓度且相同电荷数的重金属离子共存时,各离子同步被去除,但各离子之间存在干扰,越易于被离子交换的离子与其它离子共存时,其竞争能力越强,使其他离子的去除率降低越多;当待去除离子的总浓度远低于膜的交换容量时,离子共存时各离子的去除率相比离子单独存在时各离子的去除率下降幅度不大. 相似文献
48.
Comparisons of microbial community structure, in eight filter media of zeolites, anthracite, shale, vermiculite, ceramic filter media,
gravel, steel slag and bio-ceramic, were undertaken by analyzing the phospholipid fatty acid (PLFA) composition. A total of 20 fatty
acids in the range of C11 to C20 were determined but only 13 PLFAs were detected in steel slag. They consist of saturated fatty acids,
branched fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids. The variation of fatty acids was revealed in the
relative proportions of these fatty acids in di erent media. The aerobic prokaryotes were the predominant group in all media. The
PLFA composition showed significant di erences among the eight di erent media by Tukey’s honestly test. It was found that steel slag
was significantly di erent in the microbial community as compared to other filter media, probably due to its alkaline e uent. Steel
slag alone is probably not a good choice of substratum in constructed wetlands. The principle components analysis (PCA) showed that
zeolites, bio-ceramic, shale and vermiculite had a similar microbial community structure while steel slag and ceramic filter media were
distinct from other media. 相似文献
49.
A reliable and sensitive competitive real-time fluorescent quantitative immuno-PCR (RTFQ-IPCR) assay using a molecular beacon
was developed for the determination of trace fluoranthene (FL) in the environment. Under optimized assay conditions, FL can be
determined in the concentration range from 1 fg/mL to 100 ng/mL, with y = 0.194x + 7.859, and a correlation coe cient of 0.967 was
identified, with a detection limit of 0.6 fg/mL. Environmental water samples were successfully analyzed, recovery was between 90% and
116%, with intra-day relative standard deviation (RSD) of 6.7%–12.8% and inter-day RSD of 8.4%–15.2%. The results obtained from
RTFQ-IPCR were confirmed by ELISA, showing good accuracy and suitability to analyze FL in field samples. As a highly sensitive
method, the molecular beacon-based RTFQ-IPCR is acceptable and promising for providing reliable test results to make environmental
decisions. 相似文献
50.
Degradation and detoxification of microcystin-LR in drinking water by
sequential use of UV and ozone
Microcystins (MCs) produced by cyanobacteria are strong hepatotoxins and classified as possible carcinogens.MCs pose a considerable threat to human health through tainted drinking and surface waters.Herein filtrated water from a waterworks in Harbin,China,was spiked with microcystin-LR (MC-LR) extracted from a toxic scum of microcystis aeruginosa,and the spiked sample waters were treated using UV irradiation with consequent ozonation process (UV/O3),compared with ozonation at a dose range commonly applied in water treatment plants,UV irradiation at 254 nm and UV irradiation combined with ozonation (UV+O3),respectively.The remaining of toxins were analyzed using high-performance liquid chromatography and also determined using a protein phosphatase type 2A inhibition assay,which was utilized to evaluate the reduction in toxicity.Results indicated that in comparison to other three processes (O3,UV,and UV+O3),UV/O 3 process could effectively decrease both the concentration and toxicity of MC-LR at 100 μg/L level after 5 min UV irradiation with consequent 5 min ozonation at 0.2 mg/L (below 1 μg/L),while 0.5 mg/L ozone dose was required for the level below 0.1 μg/L.The addition of an UV treatment step to the existing treatment train may induce significant transformation of micropollutants and breaks down the natural organic matters into moieties unfavorable for ozone decomposition,stabilizing the ozone residual.These findings suggested that sequential use of UV and ozone may be a suitable method for the removal of these potentially hazardous microcystins from drinking water. 相似文献